In order to protect data stored in a storage system against data loss attributable to a disaster or the like, a so-called remote copy technology is used. According to the remote copy technology, a copy of data stored in a logical volume of a primary storage system (hereinafter, referred to as “primary logical volume”) is stored also in a logical volume of a secondary storage system (hereinafter, referred to as “secondary logical volume”). Data is thus made redundant, and hence, even if data stored in one logical volume is lost due to a disaster or the like, it is possible to resume a task by using data stored in another logical volume (see, for example, JP 2004-13367 A).